[v2,8/9] ALSA: virtio: introduce PCM channel map support
diff mbox series

Message ID 20210124165408.1122868-9-anton.yakovlev@opensynergy.com
State New, archived
Headers show
Series
  • [v2,1/9] uapi: virtio_ids: add a sound device type ID from OASIS spec
Related show

Commit Message

Anton Yakovlev Jan. 24, 2021, 4:54 p.m. UTC
Enumerate all available PCM channel maps and create ALSA controls.

Signed-off-by: Anton Yakovlev <anton.yakovlev@opensynergy.com>
---
 sound/virtio/Makefile       |   1 +
 sound/virtio/virtio_card.c  |  15 +++
 sound/virtio/virtio_card.h  |   8 ++
 sound/virtio/virtio_chmap.c | 237 ++++++++++++++++++++++++++++++++++++
 sound/virtio/virtio_pcm.h   |   4 +
 5 files changed, 265 insertions(+)
 create mode 100644 sound/virtio/virtio_chmap.c

Comments

Guennadi Liakhovetski Jan. 26, 2021, 9:22 a.m. UTC | #1
On Sun, 24 Jan 2021, Anton Yakovlev wrote:

> Enumerate all available PCM channel maps and create ALSA controls.
>
> Signed-off-by: Anton Yakovlev <anton.yakovlev@opensynergy.com>
> ---
> sound/virtio/Makefile       |   1 +
> sound/virtio/virtio_card.c  |  15 +++
> sound/virtio/virtio_card.h  |   8 ++
> sound/virtio/virtio_chmap.c | 237 ++++++++++++++++++++++++++++++++++++
> sound/virtio/virtio_pcm.h   |   4 +
> 5 files changed, 265 insertions(+)
> create mode 100644 sound/virtio/virtio_chmap.c

[snip]

> diff --git a/sound/virtio/virtio_chmap.c b/sound/virtio/virtio_chmap.c
> new file mode 100644
> index 000000000000..8a2ddc4dcffb
> --- /dev/null
> +++ b/sound/virtio/virtio_chmap.c
> @@ -0,0 +1,237 @@

[snip]

> +/**
> + * virtsnd_chmap_parse_cfg() - Parse the channel map configuration.
> + * @snd: VirtIO sound device.
> + *
> + * This function is called during initial device initialization.
> + *
> + * Context: Any context that permits to sleep.
> + * Return: 0 on success, -errno on failure.
> + */
> +int virtsnd_chmap_parse_cfg(struct virtio_snd *snd)
> +{
> +	struct virtio_device *vdev = snd->vdev;
> +	unsigned int i;
> +	int rc;
> +
> +	virtio_cread(vdev, struct virtio_snd_config, chmaps, &snd->nchmaps);
> +	if (!snd->nchmaps)
> +		return 0;
> +
> +	snd->chmaps = devm_kcalloc(&vdev->dev, snd->nchmaps,
> +				   sizeof(*snd->chmaps), GFP_KERNEL);
> +	if (!snd->chmaps)
> +		return -ENOMEM;
> +
> +	rc = virtsnd_ctl_query_info(snd, VIRTIO_SND_R_CHMAP_INFO, 0,
> +				    snd->nchmaps, sizeof(*snd->chmaps),
> +				    snd->chmaps);
> +	if (rc)
> +		return rc;
> +
> +	/* Count the number of channel maps per each PCM device/stream. */
> +	for (i = 0; i < snd->nchmaps; ++i) {
> +		struct virtio_snd_chmap_info *info = &snd->chmaps[i];
> +		unsigned int nid = le32_to_cpu(info->hdr.hda_fn_nid);
> +		struct virtio_pcm *pcm;
> +		struct virtio_pcm_stream *stream;
> +
> +		pcm = virtsnd_pcm_find_or_create(snd, nid);
> +		if (IS_ERR(pcm))
> +			return PTR_ERR(pcm);
> +
> +		switch (info->direction) {
> +		case VIRTIO_SND_D_OUTPUT: {
> +			stream = &pcm->streams[SNDRV_PCM_STREAM_PLAYBACK];
> +			break;
> +		}
> +		case VIRTIO_SND_D_INPUT: {
> +			stream = &pcm->streams[SNDRV_PCM_STREAM_CAPTURE];
> +			break;
> +		}
> +		default: {
> +			dev_err(&vdev->dev,
> +				"chmap #%u: unknown direction (%u)\n", i,
> +				info->direction);
> +			return -EINVAL;
> +		}
> +		}
> +
> +		stream->nchmaps++;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * virtsnd_chmap_add_ctls() - Create an ALSA control for channel maps.
> + * @pcm: ALSA PCM device.
> + * @direction: PCM stream direction (SNDRV_PCM_STREAM_XXX).
> + * @stream: VirtIO PCM stream.
> + *
> + * Context: Any context.
> + * Return: 0 on success, -errno on failure.
> + */
> +static int virtsnd_chmap_add_ctls(struct snd_pcm *pcm, int direction,
> +				  struct virtio_pcm_stream *stream)
> +{
> +	unsigned int i;
> +	int max_channels = 0;
> +
> +	for (i = 0; i < stream->nchmaps; i++)
> +		if (max_channels < stream->chmaps[i].channels)
> +			max_channels = stream->chmaps[i].channels;
> +
> +	return snd_pcm_add_chmap_ctls(pcm, direction, stream->chmaps,
> +				      max_channels, 0, NULL);
> +}
> +
> +/**
> + * virtsnd_chmap_build_devs() - Build ALSA controls for channel maps.
> + * @snd: VirtIO sound device.
> + *
> + * Context: Any context.
> + * Return: 0 on success, -errno on failure.
> + */
> +int virtsnd_chmap_build_devs(struct virtio_snd *snd)
> +{
> +	struct virtio_device *vdev = snd->vdev;
> +	struct virtio_pcm *pcm;
> +	struct virtio_pcm_stream *stream;
> +	unsigned int i;
> +	int rc;
> +
> +	/* Allocate channel map elements per each PCM device/stream. */
> +	list_for_each_entry(pcm, &snd->pcm_list, list) {
> +		for (i = 0; i < ARRAY_SIZE(pcm->streams); ++i) {
> +			stream = &pcm->streams[i];
> +
> +			if (!stream->nchmaps)
> +				continue;
> +
> +			stream->chmaps = devm_kcalloc(&vdev->dev,
> +						      stream->nchmaps + 1,
> +						      sizeof(*stream->chmaps),
> +						      GFP_KERNEL);
> +			if (!stream->chmaps)
> +				return -ENOMEM;
> +
> +			stream->nchmaps = 0;
> +		}
> +	}
> +
> +	/* Initialize channel maps per each PCM device/stream. */
> +	for (i = 0; i < snd->nchmaps; ++i) {
> +		struct virtio_snd_chmap_info *info = &snd->chmaps[i];
> +		unsigned int nid = le32_to_cpu(info->hdr.hda_fn_nid);
> +		unsigned int channels = info->channels;
> +		unsigned int ch;
> +		struct snd_pcm_chmap_elem *chmap;
> +
> +		pcm = virtsnd_pcm_find(snd, nid);
> +		if (IS_ERR(pcm))
> +			return PTR_ERR(pcm);
> +
> +		if (info->direction == VIRTIO_SND_D_OUTPUT)
> +			stream = &pcm->streams[SNDRV_PCM_STREAM_PLAYBACK];
> +		else
> +			stream = &pcm->streams[SNDRV_PCM_STREAM_CAPTURE];
> +
> +		chmap = &stream->chmaps[stream->nchmaps++];
> +
> +		if (channels > ARRAY_SIZE(chmap->map))
> +			channels = ARRAY_SIZE(chmap->map);
> +
> +		chmap->channels = channels;
> +
> +		for (ch = 0; ch < channels; ++ch) {
> +			u8 position = info->positions[ch];
> +
> +			if (position >= ARRAY_SIZE(g_v2a_position_map))
> +				return -EINVAL;
> +
> +			chmap->map[ch] = g_v2a_position_map[position];
> +		}
> +	}

You enter this function after virtsnd_chmap_parse_cfg() has run. And 
virtsnd_chmap_parse_cfg() has already found or created all the PCMs and 
counted channel maps - the same way as you do in the above loop. Wouldn't 
it be enough to reuse the result of that counting and avoid re-counting 
here?

> +
> +	/* Create an ALSA control per each PCM device/stream. */
> +	list_for_each_entry(pcm, &snd->pcm_list, list) {
> +		if (!pcm->pcm)
> +			continue;
> +
> +		for (i = 0; i < ARRAY_SIZE(pcm->streams); ++i) {
> +			stream = &pcm->streams[i];
> +
> +			if (!stream->nchmaps)
> +				continue;
> +
> +			rc = virtsnd_chmap_add_ctls(pcm->pcm, i, stream);
> +			if (rc)
> +				return rc;
> +		}
> +	}
> +
> +	return 0;
> +}
Anton Yakovlev Feb. 1, 2021, 11:21 p.m. UTC | #2
On 26.01.2021 10:22, Guennadi Liakhovetski wrote:
 > CAUTION: This email originated from outside of the organization.
 > Do not click links or open attachments unless you recognize the sender
 > and know the content is safe.
 >
 >
 > On Sun, 24 Jan 2021, Anton Yakovlev wrote:
 >
 >> Enumerate all available PCM channel maps and create ALSA controls.
 >>
 >> Signed-off-by: Anton Yakovlev <anton.yakovlev@opensynergy.com>
 >> ---
 >> sound/virtio/Makefile       |   1 +
 >> sound/virtio/virtio_card.c  |  15 +++
 >> sound/virtio/virtio_card.h  |   8 ++
 >> sound/virtio/virtio_chmap.c | 237 ++++++++++++++++++++++++++++++++++++
 >> sound/virtio/virtio_pcm.h   |   4 +
 >> 5 files changed, 265 insertions(+)
 >> create mode 100644 sound/virtio/virtio_chmap.c
 >
 > [snip]
 >
 >> diff --git a/sound/virtio/virtio_chmap.c b/sound/virtio/virtio_chmap.c
 >> new file mode 100644
 >> index 000000000000..8a2ddc4dcffb
 >> --- /dev/null
 >> +++ b/sound/virtio/virtio_chmap.c
 >> @@ -0,0 +1,237 @@
 >
 > [snip]
 >
 >> +/**
 >> + * virtsnd_chmap_parse_cfg() - Parse the channel map configuration.
 >> + * @snd: VirtIO sound device.
 >> + *
 >> + * This function is called during initial device initialization.
 >> + *
 >> + * Context: Any context that permits to sleep.
 >> + * Return: 0 on success, -errno on failure.
 >> + */
 >> +int virtsnd_chmap_parse_cfg(struct virtio_snd *snd)
 >> +{
 >> +     struct virtio_device *vdev = snd->vdev;
 >> +     unsigned int i;
 >> +     int rc;
 >> +
 >> +     virtio_cread(vdev, struct virtio_snd_config, chmaps,
 >> &snd->nchmaps);
 >> +     if (!snd->nchmaps)
 >> +             return 0;
 >> +
 >> +     snd->chmaps = devm_kcalloc(&vdev->dev, snd->nchmaps,
 >> +                                sizeof(*snd->chmaps), GFP_KERNEL);
 >> +     if (!snd->chmaps)
 >> +             return -ENOMEM;
 >> +
 >> +     rc = virtsnd_ctl_query_info(snd, VIRTIO_SND_R_CHMAP_INFO, 0,
 >> +                                 snd->nchmaps, sizeof(*snd->chmaps),
 >> +                                 snd->chmaps);
 >> +     if (rc)
 >> +             return rc;
 >> +
 >> +     /* Count the number of channel maps per each PCM device/stream. */
 >> +     for (i = 0; i < snd->nchmaps; ++i) {
 >> +             struct virtio_snd_chmap_info *info = &snd->chmaps[i];
 >> +             unsigned int nid = le32_to_cpu(info->hdr.hda_fn_nid);
 >> +             struct virtio_pcm *pcm;
 >> +             struct virtio_pcm_stream *stream;
 >> +
 >> +             pcm = virtsnd_pcm_find_or_create(snd, nid);
 >> +             if (IS_ERR(pcm))
 >> +                     return PTR_ERR(pcm);
 >> +
 >> +             switch (info->direction) {
 >> +             case VIRTIO_SND_D_OUTPUT: {
 >> +                     stream = &pcm->streams[SNDRV_PCM_STREAM_PLAYBACK];
 >> +                     break;
 >> +             }
 >> +             case VIRTIO_SND_D_INPUT: {
 >> +                     stream = &pcm->streams[SNDRV_PCM_STREAM_CAPTURE];
 >> +                     break;
 >> +             }
 >> +             default: {
 >> +                     dev_err(&vdev->dev,
 >> +                             "chmap #%u: unknown direction (%u)\n", i,
 >> +                             info->direction);
 >> +                     return -EINVAL;
 >> +             }
 >> +             }
 >> +
 >> +             stream->nchmaps++;
 >> +     }
 >> +
 >> +     return 0;
 >> +}
 >> +
 >> +/**
 >> + * virtsnd_chmap_add_ctls() - Create an ALSA control for channel maps.
 >> + * @pcm: ALSA PCM device.
 >> + * @direction: PCM stream direction (SNDRV_PCM_STREAM_XXX).
 >> + * @stream: VirtIO PCM stream.
 >> + *
 >> + * Context: Any context.
 >> + * Return: 0 on success, -errno on failure.
 >> + */
 >> +static int virtsnd_chmap_add_ctls(struct snd_pcm *pcm, int direction,
 >> +                               struct virtio_pcm_stream *stream)
 >> +{
 >> +     unsigned int i;
 >> +     int max_channels = 0;
 >> +
 >> +     for (i = 0; i < stream->nchmaps; i++)
 >> +             if (max_channels < stream->chmaps[i].channels)
 >> +                     max_channels = stream->chmaps[i].channels;
 >> +
 >> +     return snd_pcm_add_chmap_ctls(pcm, direction, stream->chmaps,
 >> +                                   max_channels, 0, NULL);
 >> +}
 >> +
 >> +/**
 >> + * virtsnd_chmap_build_devs() - Build ALSA controls for channel maps.
 >> + * @snd: VirtIO sound device.
 >> + *
 >> + * Context: Any context.
 >> + * Return: 0 on success, -errno on failure.
 >> + */
 >> +int virtsnd_chmap_build_devs(struct virtio_snd *snd)
 >> +{
 >> +     struct virtio_device *vdev = snd->vdev;
 >> +     struct virtio_pcm *pcm;
 >> +     struct virtio_pcm_stream *stream;
 >> +     unsigned int i;
 >> +     int rc;
 >> +
 >> +     /* Allocate channel map elements per each PCM device/stream. */
 >> +     list_for_each_entry(pcm, &snd->pcm_list, list) {
 >> +             for (i = 0; i < ARRAY_SIZE(pcm->streams); ++i) {
 >> +                     stream = &pcm->streams[i];
 >> +
 >> +                     if (!stream->nchmaps)
 >> +                             continue;
 >> +
 >> +                     stream->chmaps = devm_kcalloc(&vdev->dev,
 >> +                                                   stream->nchmaps + 1,
 >> +
 >> sizeof(*stream->chmaps),
 >> +                                                   GFP_KERNEL);
 >> +                     if (!stream->chmaps)
 >> +                             return -ENOMEM;
 >> +
 >> +                     stream->nchmaps = 0;
 >> +             }
 >> +     }
 >> +
 >> +     /* Initialize channel maps per each PCM device/stream. */
 >> +     for (i = 0; i < snd->nchmaps; ++i) {
 >> +             struct virtio_snd_chmap_info *info = &snd->chmaps[i];
 >> +             unsigned int nid = le32_to_cpu(info->hdr.hda_fn_nid);
 >> +             unsigned int channels = info->channels;
 >> +             unsigned int ch;
 >> +             struct snd_pcm_chmap_elem *chmap;
 >> +
 >> +             pcm = virtsnd_pcm_find(snd, nid);
 >> +             if (IS_ERR(pcm))
 >> +                     return PTR_ERR(pcm);
 >> +
 >> +             if (info->direction == VIRTIO_SND_D_OUTPUT)
 >> +                     stream = &pcm->streams[SNDRV_PCM_STREAM_PLAYBACK];
 >> +             else
 >> +                     stream = &pcm->streams[SNDRV_PCM_STREAM_CAPTURE];
 >> +
 >> +             chmap = &stream->chmaps[stream->nchmaps++];
 >> +
 >> +             if (channels > ARRAY_SIZE(chmap->map))
 >> +                     channels = ARRAY_SIZE(chmap->map);
 >> +
 >> +             chmap->channels = channels;
 >> +
 >> +             for (ch = 0; ch < channels; ++ch) {
 >> +                     u8 position = info->positions[ch];
 >> +
 >> +                     if (position >= ARRAY_SIZE(g_v2a_position_map))
 >> +                             return -EINVAL;
 >> +
 >> +                     chmap->map[ch] = g_v2a_position_map[position];
 >> +             }
 >> +     }
 >
 > You enter this function after virtsnd_chmap_parse_cfg() has run. And
 > virtsnd_chmap_parse_cfg() has already found or created all the PCMs and
 > counted channel maps - the same way as you do in the above loop. Wouldn't
 > it be enough to reuse the result of that counting and avoid re-counting
 > here?

If I understood your question right, then... it's not re-counting here. :)
It's just a referencing to each channel map for each stream in one by
one manner.


 >> +
 >> +     /* Create an ALSA control per each PCM device/stream. */
 >> +     list_for_each_entry(pcm, &snd->pcm_list, list) {
 >> +             if (!pcm->pcm)
 >> +                     continue;
 >> +
 >> +             for (i = 0; i < ARRAY_SIZE(pcm->streams); ++i) {
 >> +                     stream = &pcm->streams[i];
 >> +
 >> +                     if (!stream->nchmaps)
 >> +                             continue;
 >> +
 >> +                     rc = virtsnd_chmap_add_ctls(pcm->pcm, i, stream);
 >> +                     if (rc)
 >> +                             return rc;
 >> +             }
 >> +     }
 >> +
 >> +     return 0;
 >> +}
 >

Patch
diff mbox series

diff --git a/sound/virtio/Makefile b/sound/virtio/Makefile
index 09f485291285..2742bddb8874 100644
--- a/sound/virtio/Makefile
+++ b/sound/virtio/Makefile
@@ -4,6 +4,7 @@  obj-$(CONFIG_SND_VIRTIO) += virtio_snd.o
 
 virtio_snd-objs := \
 	virtio_card.o \
+	virtio_chmap.o \
 	virtio_ctl_msg.o \
 	virtio_jack.o \
 	virtio_pcm.o \
diff --git a/sound/virtio/virtio_card.c b/sound/virtio/virtio_card.c
index 1dd709437208..fabf91fc1c9c 100644
--- a/sound/virtio/virtio_card.c
+++ b/sound/virtio/virtio_card.c
@@ -308,6 +308,10 @@  static int virtsnd_build_devs(struct virtio_snd *snd)
 	if (rc)
 		return rc;
 
+	rc = virtsnd_chmap_parse_cfg(snd);
+	if (rc)
+		return rc;
+
 	if (snd->njacks) {
 		rc = virtsnd_jack_build_devs(snd);
 		if (rc)
@@ -320,6 +324,12 @@  static int virtsnd_build_devs(struct virtio_snd *snd)
 			return rc;
 	}
 
+	if (snd->nchmaps) {
+		rc = virtsnd_chmap_build_devs(snd);
+		if (rc)
+			return rc;
+	}
+
 	return snd_card_register(snd->card);
 }
 
@@ -438,6 +448,8 @@  static void virtsnd_remove(struct virtio_device *vdev)
 
 			if (stream->substreams)
 				devm_kfree(&vdev->dev, stream->substreams);
+			if (stream->chmaps)
+				devm_kfree(&vdev->dev, stream->chmaps);
 		}
 
 		devm_kfree(&vdev->dev, pcm);
@@ -449,6 +461,9 @@  static void virtsnd_remove(struct virtio_device *vdev)
 	if (snd->substreams)
 		devm_kfree(&vdev->dev, snd->substreams);
 
+	if (snd->chmaps)
+		devm_kfree(&vdev->dev, snd->chmaps);
+
 	devm_kfree(&vdev->dev, snd);
 
 	vdev->priv = NULL;
diff --git a/sound/virtio/virtio_card.h b/sound/virtio/virtio_card.h
index df4b0696e8c4..09c6e9ab80ca 100644
--- a/sound/virtio/virtio_card.h
+++ b/sound/virtio/virtio_card.h
@@ -52,6 +52,8 @@  struct virtio_snd_queue {
  * @njacks: Number of jacks.
  * @substreams: VirtIO PCM substreams.
  * @nsubstreams: Number of PCM substreams.
+ * @chmaps: VirtIO channel maps.
+ * @nchmaps: Number of channel maps.
  */
 struct virtio_snd {
 	struct virtio_device *vdev;
@@ -65,6 +67,8 @@  struct virtio_snd {
 	unsigned int njacks;
 	struct virtio_pcm_substream *substreams;
 	unsigned int nsubstreams;
+	struct virtio_snd_chmap_info *chmaps;
+	unsigned int nchmaps;
 };
 
 /* Message completion timeout in milliseconds (module parameter). */
@@ -110,4 +114,8 @@  int virtsnd_jack_build_devs(struct virtio_snd *snd);
 void virtsnd_jack_event(struct virtio_snd *snd,
 			struct virtio_snd_event *event);
 
+int virtsnd_chmap_parse_cfg(struct virtio_snd *snd);
+
+int virtsnd_chmap_build_devs(struct virtio_snd *snd);
+
 #endif /* VIRTIO_SND_CARD_H */
diff --git a/sound/virtio/virtio_chmap.c b/sound/virtio/virtio_chmap.c
new file mode 100644
index 000000000000..8a2ddc4dcffb
--- /dev/null
+++ b/sound/virtio/virtio_chmap.c
@@ -0,0 +1,237 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Sound card driver for virtio
+ * Copyright (C) 2020  OpenSynergy GmbH
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+#include <linux/virtio_config.h>
+
+#include "virtio_card.h"
+
+/* VirtIO->ALSA channel position map */
+static const u8 g_v2a_position_map[] = {
+	[VIRTIO_SND_CHMAP_NONE] = SNDRV_CHMAP_UNKNOWN,
+	[VIRTIO_SND_CHMAP_NA] = SNDRV_CHMAP_NA,
+	[VIRTIO_SND_CHMAP_MONO] = SNDRV_CHMAP_MONO,
+	[VIRTIO_SND_CHMAP_FL] = SNDRV_CHMAP_FL,
+	[VIRTIO_SND_CHMAP_FR] = SNDRV_CHMAP_FR,
+	[VIRTIO_SND_CHMAP_RL] = SNDRV_CHMAP_RL,
+	[VIRTIO_SND_CHMAP_RR] = SNDRV_CHMAP_RR,
+	[VIRTIO_SND_CHMAP_FC] = SNDRV_CHMAP_FC,
+	[VIRTIO_SND_CHMAP_LFE] = SNDRV_CHMAP_LFE,
+	[VIRTIO_SND_CHMAP_SL] = SNDRV_CHMAP_SL,
+	[VIRTIO_SND_CHMAP_SR] = SNDRV_CHMAP_SR,
+	[VIRTIO_SND_CHMAP_RC] = SNDRV_CHMAP_RC,
+	[VIRTIO_SND_CHMAP_FLC] = SNDRV_CHMAP_FLC,
+	[VIRTIO_SND_CHMAP_FRC] = SNDRV_CHMAP_FRC,
+	[VIRTIO_SND_CHMAP_RLC] = SNDRV_CHMAP_RLC,
+	[VIRTIO_SND_CHMAP_RRC] = SNDRV_CHMAP_RRC,
+	[VIRTIO_SND_CHMAP_FLW] = SNDRV_CHMAP_FLW,
+	[VIRTIO_SND_CHMAP_FRW] = SNDRV_CHMAP_FRW,
+	[VIRTIO_SND_CHMAP_FLH] = SNDRV_CHMAP_FLH,
+	[VIRTIO_SND_CHMAP_FCH] = SNDRV_CHMAP_FCH,
+	[VIRTIO_SND_CHMAP_FRH] = SNDRV_CHMAP_FRH,
+	[VIRTIO_SND_CHMAP_TC] = SNDRV_CHMAP_TC,
+	[VIRTIO_SND_CHMAP_TFL] = SNDRV_CHMAP_TFL,
+	[VIRTIO_SND_CHMAP_TFR] = SNDRV_CHMAP_TFR,
+	[VIRTIO_SND_CHMAP_TFC] = SNDRV_CHMAP_TFC,
+	[VIRTIO_SND_CHMAP_TRL] = SNDRV_CHMAP_TRL,
+	[VIRTIO_SND_CHMAP_TRR] = SNDRV_CHMAP_TRR,
+	[VIRTIO_SND_CHMAP_TRC] = SNDRV_CHMAP_TRC,
+	[VIRTIO_SND_CHMAP_TFLC] = SNDRV_CHMAP_TFLC,
+	[VIRTIO_SND_CHMAP_TFRC] = SNDRV_CHMAP_TFRC,
+	[VIRTIO_SND_CHMAP_TSL] = SNDRV_CHMAP_TSL,
+	[VIRTIO_SND_CHMAP_TSR] = SNDRV_CHMAP_TSR,
+	[VIRTIO_SND_CHMAP_LLFE] = SNDRV_CHMAP_LLFE,
+	[VIRTIO_SND_CHMAP_RLFE] = SNDRV_CHMAP_RLFE,
+	[VIRTIO_SND_CHMAP_BC] = SNDRV_CHMAP_BC,
+	[VIRTIO_SND_CHMAP_BLC] = SNDRV_CHMAP_BLC,
+	[VIRTIO_SND_CHMAP_BRC] = SNDRV_CHMAP_BRC
+};
+
+/**
+ * virtsnd_chmap_parse_cfg() - Parse the channel map configuration.
+ * @snd: VirtIO sound device.
+ *
+ * This function is called during initial device initialization.
+ *
+ * Context: Any context that permits to sleep.
+ * Return: 0 on success, -errno on failure.
+ */
+int virtsnd_chmap_parse_cfg(struct virtio_snd *snd)
+{
+	struct virtio_device *vdev = snd->vdev;
+	unsigned int i;
+	int rc;
+
+	virtio_cread(vdev, struct virtio_snd_config, chmaps, &snd->nchmaps);
+	if (!snd->nchmaps)
+		return 0;
+
+	snd->chmaps = devm_kcalloc(&vdev->dev, snd->nchmaps,
+				   sizeof(*snd->chmaps), GFP_KERNEL);
+	if (!snd->chmaps)
+		return -ENOMEM;
+
+	rc = virtsnd_ctl_query_info(snd, VIRTIO_SND_R_CHMAP_INFO, 0,
+				    snd->nchmaps, sizeof(*snd->chmaps),
+				    snd->chmaps);
+	if (rc)
+		return rc;
+
+	/* Count the number of channel maps per each PCM device/stream. */
+	for (i = 0; i < snd->nchmaps; ++i) {
+		struct virtio_snd_chmap_info *info = &snd->chmaps[i];
+		unsigned int nid = le32_to_cpu(info->hdr.hda_fn_nid);
+		struct virtio_pcm *pcm;
+		struct virtio_pcm_stream *stream;
+
+		pcm = virtsnd_pcm_find_or_create(snd, nid);
+		if (IS_ERR(pcm))
+			return PTR_ERR(pcm);
+
+		switch (info->direction) {
+		case VIRTIO_SND_D_OUTPUT: {
+			stream = &pcm->streams[SNDRV_PCM_STREAM_PLAYBACK];
+			break;
+		}
+		case VIRTIO_SND_D_INPUT: {
+			stream = &pcm->streams[SNDRV_PCM_STREAM_CAPTURE];
+			break;
+		}
+		default: {
+			dev_err(&vdev->dev,
+				"chmap #%u: unknown direction (%u)\n", i,
+				info->direction);
+			return -EINVAL;
+		}
+		}
+
+		stream->nchmaps++;
+	}
+
+	return 0;
+}
+
+/**
+ * virtsnd_chmap_add_ctls() - Create an ALSA control for channel maps.
+ * @pcm: ALSA PCM device.
+ * @direction: PCM stream direction (SNDRV_PCM_STREAM_XXX).
+ * @stream: VirtIO PCM stream.
+ *
+ * Context: Any context.
+ * Return: 0 on success, -errno on failure.
+ */
+static int virtsnd_chmap_add_ctls(struct snd_pcm *pcm, int direction,
+				  struct virtio_pcm_stream *stream)
+{
+	unsigned int i;
+	int max_channels = 0;
+
+	for (i = 0; i < stream->nchmaps; i++)
+		if (max_channels < stream->chmaps[i].channels)
+			max_channels = stream->chmaps[i].channels;
+
+	return snd_pcm_add_chmap_ctls(pcm, direction, stream->chmaps,
+				      max_channels, 0, NULL);
+}
+
+/**
+ * virtsnd_chmap_build_devs() - Build ALSA controls for channel maps.
+ * @snd: VirtIO sound device.
+ *
+ * Context: Any context.
+ * Return: 0 on success, -errno on failure.
+ */
+int virtsnd_chmap_build_devs(struct virtio_snd *snd)
+{
+	struct virtio_device *vdev = snd->vdev;
+	struct virtio_pcm *pcm;
+	struct virtio_pcm_stream *stream;
+	unsigned int i;
+	int rc;
+
+	/* Allocate channel map elements per each PCM device/stream. */
+	list_for_each_entry(pcm, &snd->pcm_list, list) {
+		for (i = 0; i < ARRAY_SIZE(pcm->streams); ++i) {
+			stream = &pcm->streams[i];
+
+			if (!stream->nchmaps)
+				continue;
+
+			stream->chmaps = devm_kcalloc(&vdev->dev,
+						      stream->nchmaps + 1,
+						      sizeof(*stream->chmaps),
+						      GFP_KERNEL);
+			if (!stream->chmaps)
+				return -ENOMEM;
+
+			stream->nchmaps = 0;
+		}
+	}
+
+	/* Initialize channel maps per each PCM device/stream. */
+	for (i = 0; i < snd->nchmaps; ++i) {
+		struct virtio_snd_chmap_info *info = &snd->chmaps[i];
+		unsigned int nid = le32_to_cpu(info->hdr.hda_fn_nid);
+		unsigned int channels = info->channels;
+		unsigned int ch;
+		struct snd_pcm_chmap_elem *chmap;
+
+		pcm = virtsnd_pcm_find(snd, nid);
+		if (IS_ERR(pcm))
+			return PTR_ERR(pcm);
+
+		if (info->direction == VIRTIO_SND_D_OUTPUT)
+			stream = &pcm->streams[SNDRV_PCM_STREAM_PLAYBACK];
+		else
+			stream = &pcm->streams[SNDRV_PCM_STREAM_CAPTURE];
+
+		chmap = &stream->chmaps[stream->nchmaps++];
+
+		if (channels > ARRAY_SIZE(chmap->map))
+			channels = ARRAY_SIZE(chmap->map);
+
+		chmap->channels = channels;
+
+		for (ch = 0; ch < channels; ++ch) {
+			u8 position = info->positions[ch];
+
+			if (position >= ARRAY_SIZE(g_v2a_position_map))
+				return -EINVAL;
+
+			chmap->map[ch] = g_v2a_position_map[position];
+		}
+	}
+
+	/* Create an ALSA control per each PCM device/stream. */
+	list_for_each_entry(pcm, &snd->pcm_list, list) {
+		if (!pcm->pcm)
+			continue;
+
+		for (i = 0; i < ARRAY_SIZE(pcm->streams); ++i) {
+			stream = &pcm->streams[i];
+
+			if (!stream->nchmaps)
+				continue;
+
+			rc = virtsnd_chmap_add_ctls(pcm->pcm, i, stream);
+			if (rc)
+				return rc;
+		}
+	}
+
+	return 0;
+}
diff --git a/sound/virtio/virtio_pcm.h b/sound/virtio/virtio_pcm.h
index fe467bc05d8b..a326b921b947 100644
--- a/sound/virtio/virtio_pcm.h
+++ b/sound/virtio/virtio_pcm.h
@@ -70,10 +70,14 @@  struct virtio_pcm_substream {
  * struct virtio_pcm_stream - VirtIO PCM stream.
  * @substreams: Virtio substreams belonging to the stream.
  * @nsubstreams: Number of substreams.
+ * @chmaps: Kernel channel maps belonging to the stream.
+ * @nchmaps: Number of channel maps.
  */
 struct virtio_pcm_stream {
 	struct virtio_pcm_substream **substreams;
 	unsigned int nsubstreams;
+	struct snd_pcm_chmap_elem *chmaps;
+	unsigned int nchmaps;
 };
 
 /**